1. Technical Field of the Invention
This invention relates to a potentially crimpable polyolefin composite fiber which potential crimp emerge under thermal treatment, and a non-woven fabric using the same.
2. Description of Related Art
As one of the methods for obtaining lofty non-woven fabrics, it has been a conventionally known method to use fiber with a zigzag shape crimp given by mechanical crimping means such as a stuffer box, or using a side-by-side or an eccentric sheath-core composite fiber spirally crimped by means for generating strain in the fiber such as stretching.
For example, proposed in Japanese Patent Application No. Hei 1-5093 (Publication No. Hei 2-191720) is a sheath-core composite fiber arranged with an ethylene-propylene random copolymer mainly as the sheath component and a crystalline polypropylene as the core component. This fiber is aimed to obtain a lofty non-woven, wherein potential crimp emerge under thermal treatment in the non-woven fabric production process by taking advantage of thermal shrinkage of the ethylene-propylene random copolymer arranged as the sheath component. However, friction against metals of the ethylene-propylene random copolymer of the sheath component is much higher than other resins generally used for fibers, for example, high density polyethylene, so that this fiber is not ejected well from a carding machine, and it is difficult to obtain a uniform web; also the obtained non-woven fabric has peculiar greasy or sticky feeling resulting from the nature of raw material of the sheath component. Further, the fiber is generally opened with hopper feeder and transferred to the carding machine through an air blowing duct, but the fiber having high friction against metals has an impaired transferring problem that the fiber sticks to the inside of air blowing duct. In the case of spinning continuous filaments of composite fiber combining these resins with spun-bond method in which the carding process is not required, it is also a problem that the fiber is not well opened due to the fiber's inter-friction caused by the ethylene-propylene random copolymer covering the surface of the fiber, and web accumulated onto conveyer is not uniform. As mentioned the above, lofty and high quality non-woven fabric using potentially crimpable fiber has not been actually obtained up to now, but requirement for lofty non-woven fabric having better touch feeling has been heightened, with escalated market competition of disposable diapers and sanitary materials.
This invention aims to solve the above problem and to provide a lofty non-woven fabric having good touch feeling and its raw material of a potentially crimpable fiber.